1. Field of the Invention
The present invention relates to a light-emitting apparatus, more specifically to a light-emitting apparatus in which a focusing position of light emitted from a light-emitting source, broadening and narrowing directions of emitted light, and changing the illuminating area are electrically controlled.
2. Description of Related Art
There is generally known that a light-emitting apparatus includes a light-emitting source such as a light-emitting diode (LED) element, a filament lamp or the like, and a convex lens disposed in front of an emission surface of the light-emitting source, and the convex lens works to focus light emitted from the emission surface of the light-emitting source on an object.
An example of a conventional light-emitting apparatus is shown in FIG. 8. The light-emitting apparatus has a case 1, an LED element 2 disposed in the case 1, and a normal convex lens 3 attached to the case 1 to face the LED element 2. The case 1 has a truncated conical-or truncated pyramidal-shaped concave portion 4, and the inner surface of the concave portion 4 has a reflecting surface 5 configured to increase reflection efficiency of light. The convex lens 3 is structured to focus light emitted from the LED element 2 to the object positioned apart from the light-emitting apparatus by a predetermined distance and to illuminate the object. The conventional light-emitting apparatus is used for reading CDs or the like and headlights of automobiles.
In addition, a conventional light-emitting apparatus having a structure similar to that of the above-mentioned light-emitting apparatus is disclosed in JP 2003-158301A, FIG. 3, for reference.
However, because each of the conventional light-emitting apparatuses as described above uses the normal convex lens 3 having a fixed focal length, an angle or focusing position of light emitted from the convex lens cannot be changed. In other words, an illumination scope, light-intensity distribution, or directions of emitted light cannot be changed in the conventional light-emitting apparatuses.
It is considered that a focal length for one lens or a plurality of lenses disposed in front of the light-emitting source is changed in order to change the illumination scope and so on. In order to achieve the change for the focal length, directions of emitted light, and the illuminating area a mechanism must be provided to move a focal length of one lens or at least one lens of the plurality of lenses relative to the light-emitting source, there is a problem that the light-emitting apparatus has a complicated structure.